science

Noise map

Noise map is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Noise map rather than just read about it. In short: A noise map is a graphic representation of the sound level distribution and the propagation of sound waves in a given region, for a defined period. Definition Although some previous approaches had been made, the main international agreement and definitions for noise mapping were born in relation to the Environmental noise directive of the European Parliament and Council (Directive 2002/49/EC of 25 June 2002, commonl…

Key takeaways

Noise map belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Noise map to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Noise map from memory before moving on to harder problems.

Reference excerpt

A noise map is a graphic representation of the sound level distribution and the propagation of sound waves in a given region, for a defined period.

Definition Although some previous approaches had been made, the main international agreement and definitions for noise mapping were born in relation to the Environmental noise directive of the European Parliament and Council (Directive 2002/49/EC of 25 June 2002, commonly referred to as the END). The END defines in Article 3: "noise indicator shall mean a physical scale for the description of environmental noise, which has a relationship with a harmful effect; strategic noise map shall mean a map designed for the global assessment of noise exposure in a given area due to different noise sources or for overall predictions for such an area." EU Member States are required to produce strategic noise maps in their main cities, near the main transport infrastructure and industrial sites. The main goals of the END are to make a diagnosis of noise pollution in Europe that can lead to noise management plans and acoustical planning. The term 'strategic' is very important in this definition, because the management of environmental noise must be made for the long-term. This map can be used for scientists, politicians or other interested parties.

Production The main noise indicators for noise mapping are long-term averaged sound levels, determined over all the correspondent periods of a year. All of these indicators may be defined in terms of A-weighted decibels (dBA, dB(A)). The result can be determined by computation or measurement methods. Computation methods are widely preferred, because of the large amount of yearly averaged locations required. Using either approach, a grid of receivers must be defined in order to measure or calculate noise levels. When results are obtained, using GIS tools, spatial interpolation must be applied in order to give a continuous graphical representation of sound levels. According to the END five dBA ranges are used for this contour (isoline) representation. The maps may be useful for planning stages, or for prior evaluation of action plans, or determination of most polluted areas. With a strategic noise map, furthermore, an evaluation is possible to show the number of people exposed within dBA ranges. Facade sound levels must be calculated or estimated from the previous map.

Simulation tools There are several methods for making noise maps. Some of them use empirical models (for instance, INM was formerly used for airport noise mapping), but most of the models are based on the physics of propagation of sound outdoors (defined in ISO 9613). Today the use of software packages has made the process easier, but the accuracy of results depends on the quality of input data. The main challenges for the acoustic consultant include the collection of data, creating useful models of the street network and a good digital terrain model (DTM). For train and road traffic noise, the description of the sources is usually made in terms of parameters such as speed, number of vehicles etc. Measurements are used for the validation of results. For industrial noise map production, the most important thing is the description of noise sources: sound power levels (emission), directivity, working periods. Although some databases can be found, in some cases it is necessary to make measurements (ISO 3740) for describing the source. To calculate the noise propagation, it is necessary to create a model with points, lines and areas for the noise sources. The creation of a good acoustic model can be quite complicated. Simulation tools are very useful specially at planning stages, where measurements are not possible. The consultant can evaluate the effectiveness for decisions in action plans, in order to minimize noise.

External links UK Department for Environment, Food & Rural Affairs: Noise Mapping England European Commission: Noise policy FHWA Traffic Noise Model Switzerland: Road traffic: determination of emissions and immissions; see also enforcement relevant documents and tools

References

Illustrations

Worked examples

Example 1 — a first encounter with Noise map

Start with the simplest possible case. Write down what Noise map claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Noise map before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Noise map ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Noise map

In research: Noise map appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Noise map in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Noise map is common in secondary-school and first-year university syllabi. It links to neighbouring topics Noise pollution, Sound measurements, Types of map, so understanding it makes those chapters shorter.
In everyday life: Look for Noise map outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Noise map in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Noise map means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Noise map out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Noise map in simple terms?

A noise map is a graphic representation of the sound level distribution and the propagation of sound waves in a given region, for a defined period. Definition Although some previous approaches had been made, the main international agreement and definitions for noise mapping were born in relation to…

Why does Noise map matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Noise map?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Noise map.